Generic name: Guanfacine hydrochloride.

Tenex is an antihypertensive. It works to reduce blood pressure by reducing nerve impulses to the heart and arteries. 

Quick Facts About Tenex


Used to treat high blood pressure. May be prescribed alone or with other high blood pressure medications such as thiazide diuretics.

Tenex Dosage

May take several weeks to observe full effects of medication. Take Tenex regularly for it to be effective; continue to take even if you feel well. Causes drowsiness, so take at bedtime. Do not stop taking abruptly.

  • Usual adult dose: 1 milligram per day taken at bedtime. Doctor may increase after 3 to 4 weeks up to 2 milligrams per day. Doctor will adjust doses if you have kidney damage and are also taking phenytoin (Dilantin).
  • Usual child dose: not generally prescribed for children under 12 years.
  • Missed dose: take as soon as possible, unless almost time for next dose. In that case, do not take missed dose; go back to regular schedule. Do hot double doses.

Tenex Side Effects

Overdose symptoms:

drowsiness, lethargy, slowed heartbeat, very low blood pressure. If you suspect an overdose, immediately seek medical attention.

More common side effects: constipation, dizziness, dry mouth, fatigue, headache, impotence, sleepiness, weakness.

Less common or rare Tenex side effects: abdominal pain, amnesia, breathing difficulties, chest pain, confusion, conjunctivitis (pinkeye), decreased sex drive, depression, diarrhea, difficulty swallowing, fainting, heart palpitations, indigestion, insomnia, itching, leg cramps, malaise (vague feeling of illness), nausea, numbness or tingling skin, purplish skin spots, rash and peeling, runny nose, skin inflammation, slow heartbeat, upset stomach, urinary incontinence, vision disturbance.


Inform your doctor before combining Tenex with:

barbiturates such as Amytal, Seconal, and Tulnal; benzodiazepines such as Tranxene, Valium, and Xanax; phenothiazines such as Mellaril, Stelazine, and Thorazine; phenytom (Dilantin).

No known food/other substance interactions.

Special Cautions

Should not be taken if pregnant. If pregnant or planning to become pregnant, inform your doctor immediately. Not known if Tenex appears in breast milk.

No special precautions apply to seniors.

Not generally prescribed for children under 12.

  • May cause drowsiness and dizziness and impair your ability to drive a car or operate machinery. Do not take part in any activity that requires alertness.
  • Doctor should closely monitor during Tenex therapy if you have: chronic kidney or liver failure, heart disease, history of stroke, recent heart attack
  • If you stop taking abruptly, may cause nervousness, rapid pulse, anxiety, heartbeat irregularities, and rebound high blood pressure — higher blood pressure than before treatment began. Rebound high blood pressure usually occurs 2 to 4 days after the end of therapy, and will disappear over 2 to 4 days.


HealthSurvey.org provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Tenex side effects, please contact your healthcare provider